I've been using NWP for years, but am still challenged with the fact that every time I use Command Down Arrow the cursor drops to the very bottom of the document - sometimes 40 or 50 pages below where I am.

How would I go about creating a macro or command that took the cursor down one paragraph at a time, using Command Down Arrow, and up one paragraph at a time using Command Up Arrow?

As Hamid mentions, there is a key sequence to navigate by paragraph. These kind of arrow key navigation shortcuts are system-wide and established by OSX, and it's not so easy to change them (see more below), and you cannot remap them to activate a macro in Nisus Writer.

That said, if you really want to change the behavior of Command + Down Arrow you can do it, but only for your Mac as a whole (ie: all modern OSX apps will be changed). Have a look at this web page, under "Default key bindings", but be warned: it's intensive stuff. I'll attach a DefaultKeyBinding.dict file here that does remap Command + Up/Down Arrow to move to the start/end of the current paragraph.

Thanks Martin. You've reminded me of something I research a few years ago - that the DefaultKeyBinding.dict file needs to be replaced. Before I go through that I think I'll try and adjust to using Option Up & Down arrow, instead.

Thanks also for posting the DefaultKeyBinding.dict file, in case I want to use it later.